Prevalence of Electrographic Seizures After Convulsive Status Epilepticus Clarified in Children

By Brian Hoyle

Washington, DC -- December 10, 2013 --The prevalence of persistent electrographic seizures after convulsive status epilepticus (CSE) in paediatric patients with epilepsy has been clarified, according to a study presented here at the 67th Annual Meeting of the American Epilepsy Society (AES).

To date, there are no data on the proportion of children in whom electrographic seizures persist after CSE terminates. The objective of our study was to describe the occurrence and characteristics of electrographic seizures following CSE in children, said Iván Sánchez Fernández, MD, Department of Neonatology, Hospital Sant Joan de Déu, Barcelona, Spain, on December 9.

The 11-centre retrospective study involved 98 consecutive children (aged 1 month to 21 years, median 5 years; 53 males) who presented with CSE and underwent continuous electroencephalographic (EEG) monitoring in paediatric intensive care units. The age at onset of CSE was 5 years (range, 2.0-21.4 years). Of the patients, 60.2% had exhibited prior developmental delay, and 57.1% had been diagnosed as having epilepsy.

Electrographic seizures with or without clinical correlates were identified in 32 patients (33%), of whom 11 (34.4%) had EEG-only seizures, 17 (53.1%) had electroclinical seizures, and 4 (12.5%) had unknown clinical correlate because of lack of data. Fifteen (46.9%) of these patients had electrographic status epilepticus, with 6 (40%) classified as continuous status epilepticus (defined as electrographic seizures lasting >30 minutes) and 9 (60%) as intermittent status epilepticus (defined as recurring electrographic seizures totalling >50% of a 1-hour epoch).

Among 32 of the patients, the typical duration of epileptic seizures was up to 1 minute in 11 patients (34.4%), up to 5 minutes in 10 (31.3%), up to 30 minutes in 7 (21.9%), and >30 minutes in 4 (12.5%). The onset location of seizures among 39 patients was focal in 16 (41%), multifocal in 8 (20.5%), generalised in 12 (30.8%), and unknown in 3 (7.7%).

Factors significantly associated with the development of electrographic seizures after CSE were a prior diagnosis of epilepsy (<i>P</i> = .029), an abnormal initial background category on continuous EEG (<i>P</i> = .045), and the presence of interictal epileptiform discharges (<i>P </i>= .0005).

The median (interquartile range) duration of stay in the paediatric intensive care unit was 3 (2-10) days. Hospitalisation was longer for children with electrographic seizures than those without electrographic seizures (9.5 vs 2.0; <i>P</i> = .0001). Four deaths that occurred before hospital discharge were not related to electrographic seizures.

Our study clarifies the prevalence and characteristics of persistent electrographic seizures after CSE in children, said Dr. Fernández. After CSE, one-third of paediatric patients who underwent EEG monitoring experienced electrographic seizures. Among these, one-third had no clinical correlate with their seizures.

A prior diagnosis of epilepsy and the presence of interictal epileptiform discharges were associated with the occurrence of electrographic seizures. Electrographic seizures were associated with a longer stay in the intensive care unit, the researchers concluded.